Metachondromatosis (MC) is a rare autosomal dominant disorder characterized by concurrent exostoses and enchondromatosis. Clinically distinct from multiple hereditary exostoses (MHE, caused by EXT1/EXT2 mutations) and other enchondromatosis syndromes, MC primarily affects the epiphyses of the extremities. Unlike MHE, MC lesions possess a fibrous capsule and grow toward the adjacent joint rather than away from it, with a lower risk of malignant transformation. Partial regression of enchondromas occurs in approximately one-third of cases. Surgical intervention is reserved for symptomatic lesions. PTPN11 mutations, affecting the RAS signaling pathway, are identified in 50% of cases. They are different from the PTPN11 mutations causing Noonan and LEOPARD syndromes.
We present a case series of four patients (including two siblings) with multiple bony lesions, aged 6 to 30 years, followed for a mean of 7.75 years (range: 3-10). A PTPN11 mutation was detected in three cases (75%) including the siblings. Lesions predominantly involved the hands and fingers, with atypical features. Patients underwent an average of one surgery (range: 0-3), with all exhibiting spontaneous regression of the lesions and favorable, asymptomatic outcomes.
This series highlights key distinctions between MC and MHE, emphasizing the potential for spontaneous resolution in MC, in contrast to the frequent surgical management required for MHE.
International Journal of Case Reports in Orthopaedics
